The current state of the art in wavefront sensing and control and thermal stability control for telescopes is performed periodically. A telescope's primary mirror can comprise a plurality of mirror segments, the primary mirror can be a single unit. Fine phasing can be performed using each primary mirror segment. This can be achieved using phase retrieval methods that require moving a filter wheel, pointing at a star, and using the main science camera to take an image. For the current state of the art, fine phasing updates of the primary mirror segments occur approximately once every 14 days. In between, the architecture for the telescope relies on passive thermal stability to meet the allocated wavefront error allocation, a highly challenging capability. Wavefront sensing and control, and passive thermal stability architecture, will not suffice for mirrors designed to be used in the future, because the mirror and composite structure is not sufficiently stable to meet an acceptable allocation, for example, about 5 nm root means squared.
Furthermore, some systems are very complex and expensive and can include edge sensors and laser trusses. Thus, a technique is needed to improve the thermal stability and fine phasing update architecture of a UV-optical telescope. The system and method described herein have limited impact on the overall complexity of the system, particularly of the primary mirror system.